This application proposes scientific research on chiropractic by engineering and biological scientists at the University of Colorado as Co-Principal Investigators and Doctors of Chiropractic as Associate Investigators. The broad objective is to critically explore the spinal physiology underlying chiropractic with bioengineering techniques. As specific research activities we propose: a. To complete development of a computer-aided method of x-ray analysis for spinal subluxation investigation. b. To develop a digital-computer simulation model for spinal movement and structural analysis together with computer graphics display of results, with emphasis on the biomechanical aspects of spinal subluxation. c. To determine biomechanical properties of spinal discs, ligaments, and muscles by the laboratory testing techniques of engineering mechanics. d. To determine the effect of spinal disorders on gait. e. To undertake neurophysiological studies of spinal nerve compression and joint fixation. f. To initiate studies into the chemical message wich signals tissue damage and pain. g. To study protein alterations and synaptosomes from the spinal cord associated with nerve and cord compression. h. To rigorously investigate the characteristics of the spinal subluxation complex with combined structural, mechanical, neurophysiological, and neurochemical experiments on animals.